Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K19/00—Liquid crystal materials
  • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
  • C09K19/36—Steroidal liquid crystal compounds
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
  • C09B13/00—Oxyketone dyes
  • C09B13/02—Oxyketone dyes of the naphthalene series, e.g. naphthazarin
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K19/00—Liquid crystal materials
  • C09K19/52—Liquid crystal materials characterised by components which are not liquid crystals, e.g. additives with special physical aspect: solvents, solid particles
  • C09K19/60—Pleochroic dyes

Definitions

• the electrooptical effect of the display can be produced by embedding pleochroic dyestuffs ("guest phase”) in a liquid crystal matrix ("host phase”).
• guest phase pleochroic dyestuffs
• host phase liquid crystal matrix
• the dyestuffs which have hitherto been used for this purpose fulfill the imposed requirements (for example high order parameter, satisfactory solubility in the host phase, and stability to UV and visible light and to voltages of up to about 20 V) only to an unsatisfactory extent.
• pleochroic dyestuffs in particular red dyestuffs, which do not have the disadvantage of the known dyestuffs, or which display them only to a lesser extent, and which are suitable as constituents of liquid crystal dielectrics.
• the present invention has achieved these objects by providing new liquid crystal dielectrics containing one or more pleochroic dyestuffs for electrooptical display elements, and which contain at least one dyestuff of formula I ##STR2## wherein R 1 and R 2 are identical or different and are alkyl or alkoxy each of 3 to 8 C atoms or a group Z--Y--, or one of R 1 and R 2 can also be hydrogen, methyl, ethyl, methoxy or ethoxy: Z is R--Ph--, R--Ph--Ph--, R--Cy--, R--Cy--Cy--, R--Cy---Ph-- or R--Ph--Cy--; Ph is in each case a 1,4-phenylene radical: Cy is in each case a 1,4-cyclohexylene radical: Y is --CH 2 --, --O--, --S--, --NH---, --CH 2 CH
• this invention relates to the liquid crystal dielectric mentioned above, and furthermore to compounds of formula I, with the proviso that (a) R 1 and R 2 are not simultaneously p-tolylthio and not simultaneously anilino; (b) R 1 is p-tolylthio, anilino or p-anisidino only when R 2 is other than H; and moreover to a process for the preparation of the latter compounds, comprising hydrolyzing a diaminonaphthoquinone of formula II ##STR3## wherein R 1 and R 2 are as defined above, or for the preparation of a compound of formula I wherein R 1 is Z--S-- or Z--NH--, reacting a naphthazarine derivative of formula III ##STR4## wherein R 2 is as defined above, with a compound of formula IV
• X is --S-- or --NH-- and Z is as defined above.
• This invention also relates to the use of a compound of formula I as a constituent of a liquid crystal dielectric useful in electrooptical display elements, and to an electrooptical display element based on a guest/host liquid crystal cell, containing a liquid crystal dielectric of this invention.
• R 1 , R 2 , Z, Ph, Cy, Y, R and X are as defined above, unless expressly indicated otherwise.
• alkyl and alkoxy groups are preferably straight-chained. They preferably contain 3-7 C atoms.
• alkyl is, in particular, propyl, butyl, pentyl, hexyl or heptyl, and also preferably octyl, isopropyl, 2-methyl-propyl, 2-methyl-butyl, 3-methyl-butyl, 2-methyl-pentyl, 3-methyl-pentyl, 1-methyl-hexyl, 2-ethyl-hexyl or 1-methyl-heptyl;
• alkoxy is, in particular, propoxy, butoxy, pentyloxy, hexyloxy or heptyloxy, and furthermore preferably octyloxy, isopropoxy, 2-methyl-propoxy, 2-methyl-butoxy, 3-methyl-butoxy, 2-methyl-pentyloxy, 3-methyl-pentyloxy, 1-methylhexyloxy, 2-eth
• the radical Z is preferably R--Ph--, and the radical Y is preferably --S--, --NH-- or a direct bond.
• the invention particularly relates to those compounds of formula I in which at least one of the radicals mentioned has one of the abovementioned preferred meanings.
• Some preferred groups of compounds may be expressed by the following partial formulae Ia to Id, which correspond to formula I and wherein the radicals not defined in more detail have the meanings given for formula I, but wherein, in
• R 1 is R--Ph--Y-- and Y is --S--, --NH-- or a direct bond;
• R 1 is R--Ph--S-- and R 2 is H or R--Ph--S, wherein R in the groups R 1 and R 2 can be identical or different;
• R 1 is R--Ph--NH-- and R 2 is H;
• R 1 is R--Ph-- and R 2 is H.
• the compounds of formula I are moreover prepared by methods which are known per se, such as those described in the literature (for example in the standard works, such as Houben-Weyl, Methoden der Organischen Chemie (Methods of Organic Chemistry), Georg-Thieme-Verlag, Stuttgart, whose disclosure is incorporated by reference herein), and in particular under reaction conditions which are known and suitable for the reactions mentioned. It is also possible to use variants which are known per se but are not mentioned here in more detail.
• the starting substances can also be formed in situ, in a manner such that they are not isolated from the reaction mixture, but are immediately further reacted to give the compounds of formula I.
• the compounds of formula I can be obtained, in particular, by hydrolysis of the diaminonaphthoquinones of formula II, advantageously by reaction with a mineral acid, such as sulfuric acid, in about 2 to 98%, preferably about 10 to 30%, aqueous solution, at temperatures of about 10° to about 150°, preferably of about 60° to 110°.
• a mineral acid such as sulfuric acid
• the starting substances of formula II can be obtained conventionally, for example, by reacting the corresponding 1,5-dinitro-3-R 1 -7-R 2 -naphthalenes with sulfur in oleum, and those of formula II in which R 1 and/or R 2 are R--Ph-- can also be obtained conventionally by arylation of 4,8-diamino-1,5-naphthoquinone with diazonium salts of the formula R--Ph--N 2 + An - (wherein An - is an anion customarily used with aromatic diazonium salts, for example chloride, bromide or sulfate), or by an Ullmann reaction from 4,8-diamino-2,6-dibromo-1,5-naphthoquinone and iodobenzene derivatives of the formula R--Ph--I.
• the reaction conditions can be controlled such that this compound reacts with one or two molecules of IV. If, for example, the mercaptan Z--SH is used in excess, the disubstituted product (I, R 1 and R 2 are Z--S--) is predominantly formed, and if III (R 2 is H) is used in excess, the monosubstituted product (I, R 1 is Z--S-- and R 2 is H) is predominantly formed.
• the dielectrics according to this invention comprise 2 to 15, preferably 3 to 12, constituents, at least one of which is a naphthoquinone dyestuff of formula I.
• the other constituents are preferably chosen from nematic or nematogenic substances, in particular the known substances from the classes of azoxybenzenes, benzylideneanilines, biphenyls, terphenyls, phenyl or cyclohexylbenzoates, phenyl or cyclohexyl cyclohexanecarboxylates, phenylcyclohexanes, cyclohexylbiphenyls, cyclohexylcyclohexanes, cyclohexylnaphthalenes, 1,4-bis-cyclohexylbenzenes, 4,4'-bis-cyclohexylbiphenyls, phenyl- or cyclohexyl-pyrimidines,
• a and E are each a carbocyclic of heterocyclic ring system from the group of 1,4-disubstituted benzene and cyclohexane rings, 4,4'-disubstituted biphenyl, phenylcyclohexane and cyclohexylcyclohexane systems, 2,5-disubstituted pyrimidine and 1,3-dioxane rings, 2,6-disubstituted naphthalene, di- and tetrahydronaphthalene, quinazoline and tetrahydroquinazoline;
• B is --CH ⁇ CH--, --CH ⁇ CG--, --C.tbd.C--, --CO--O--, --CO--S, --CH ⁇ N--, --N ⁇ N--, --N(O) ⁇ N--, --CH ⁇ N(O)--, --CH 2 --CH 2 --, --CH 2 --O--,
• the dielectrics according to this invention contain as a rule 0.1 to 15, preferably 0.5 to 10 and in particular 1 to 5, percent by weight of one or more compounds of formula I. Otherwise, the compositions of such dielectrics are fully conventional.
• the dielectrics according to this invention are prepared in a manner which is customary per se. As a rule, the constituent used in the smaller amount is dissolved in the constituent which makes up the main constituent, preferably at elevated temperature. If a temperature above the clar point of the main constituent is chosen, it is particularly easy to observe the completeness of the solution operation.
• the liquid crystal dielectrics according to this invention can be modified by suitable additives such that they can be used in all the types of guest/host display elements which have hitherto been disclosed.
• suitable additives are known to the expert and are described in detail in the literature.
• substances for modifying the dielectric anisotropy, the viscosity, the conductivity and/or the orientation of the nematic phases may be added.
• Such substances are described in, for example, German Offenlegungsschriften Nos. 2,209,127, 2,240,864, 2,321,632, 2,338,281, 2,450,088, 2,637,430, 2,853,728 and 2,902,177, all of whose disclosures are incorporated by reference herein.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Crystallography & Structural Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Liquid Crystal Substances (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Liquid Crystal (AREA)
• Devices For Indicating Variable Information By Combining Individual Elements (AREA)
• Heterocyclic Compounds That Contain Two Or More Ring Oxygen Atoms (AREA)
• Heterocyclic Carbon Compounds Containing A Hetero Ring Having Oxygen Or Sulfur (AREA)

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Citations (24)

• 1982
  • 1982-01-28 DE DE19823202761 patent/DE3202761A1/de not_active Withdrawn
• 1983
  • 1983-01-17 EP EP83100346A patent/EP0085335B1/fr not_active Expired
  • 1983-01-17 AT AT83100346T patent/ATE18915T1/de not_active IP Right Cessation
  • 1983-01-17 DE DE8383100346T patent/DE3362737D1/de not_active Expired
  • 1983-01-26 KR KR1019830000294A patent/KR840003276A/ko not_active Withdrawn
  • 1983-01-26 DD DD83247475A patent/DD206785A5/de unknown
  • 1983-01-26 CA CA000420535A patent/CA1198121A/fr not_active Expired
  • 1983-01-28 JP JP58011616A patent/JPS58129055A/ja active Pending
  • 1983-01-28 US US06/462,153 patent/US4499004A/en not_active Expired - Fee Related
• 1986
  • 1986-07-24 SG SG64386A patent/SG64386G/en unknown
  • 1986-12-11 HK HK970/86A patent/HK97086A/xx unknown

Patent Citations (24)

Non-Patent Citations (16)

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